Go Maybelle K, Richard John P
Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, USA.
Bioorg Chem. 2008 Dec;36(6):295-8. doi: 10.1016/j.bioorg.2008.08.003. Epub 2008 Sep 21.
The non-enzymatic reaction of 5'-deoxypyridoxal (DPL) with l-alanine in water at 25 degrees C was investigated. DPL reacts with alanine to form an imine, which then undergoes deprotonation at the alpha-amino carbon of alanine to form a resonance delocalized DPL-stabilized carbanion. At early reaction times the only detectable products are pyruvate and the dimeric species formed by addition of the alpha-pyridine stabilized carbanion to DPL. No Claisen-type products of addition of the alpha-amino carbanion to DPL, as was previously reported to form from the reaction between DPL and glycine [K. Toth, T.L. Amyes, J.P. Richard, J.P.G. Malthouse, M.E. Ni Beilliu, J. Am. Chem. Soc. 126 (2004) 10538-10539], are observed. The electrophile reacts instead at the alpha-pyridyl carbon. This dimer is in chemical equilibrium with reactants. At longer reaction times about 50% of DPL is converted to 5'-deoxypyridoxamine, the thermodynamically favored product of formal transamination of DPL.
研究了25℃下5'-脱氧吡哆醛（DPL）与L-丙氨酸在水中的非酶反应。DPL与丙氨酸反应形成亚胺，然后在丙氨酸的α-氨基碳处发生去质子化，形成共振离域的DPL稳定碳负离子。在反应初期，唯一可检测到的产物是丙酮酸以及由α-吡啶稳定的碳负离子加成到DPL上形成的二聚体。未观察到如先前报道的由DPL与甘氨酸反应形成的α-氨基碳负离子加成到DPL上的克莱森型产物[K.托特，T.L.艾姆斯，J.P.理查德，J.P.G.马尔特豪斯，M.E.尼·贝柳，《美国化学会志》126（2004）10538 - 10539]。亲电试剂反而在α-吡啶基碳处发生反应。该二聚体与反应物处于化学平衡。在较长反应时间时，约50%的DPL转化为5'-脱氧吡哆胺，这是DPL形式上转氨作用的热力学有利产物。
